Platen reversing means for a printing apparatus



April 1969 v. H. FOERSTERLING 3,438,477

PLATEN REVERSING MEANS FOR A PRINTING APPARATUS Filed July 5, 1966 1POWER SOURCE b AUTOMATIC, INVENTOR.

E 59 T EA 53$ ERNON H. FOERSTERLING *64 so 2 BY 6 UN: $1M

Fig) ATTORNEYS" United States Patent U.S. Cl. 197-114 Claims ABSTRACT OFTHE DISCLOSURE In a printing apparatus of the type including a platenfor supporting a printing medium and means for driving the platenforwardly, means for reversing the platen in a step-by-step manner. Thereversing means comprises first ratchet means arranged to move theplaten in the reverse direction, second ratchet means arranged to stopmovement of the platen in the reverse direction and electricallyoperated means for substantially simultaneously operating the first andsecond ratchet means to move said platen a predetermined amount in thereverse direction. Manually operated means is provided for energizingthe electrically operated means and switch means is provided fordeenergizing the electrically operated means when the platen is movedsaid predetermined amount, the switch means being responsive to movementof the electrically operated means. Preferably, circuit means isprovided for automatically operating the electrically operated means,the circuit means being connected in parallel with the manually operatedmeans and responsive to coded input means. Also, preferably, means forimparting a code index to a tape is provided, the circuit means beingarranged to actuate the code index imparting means when the electrically operated means is energized by the manually operated means.

The present invention relates to printing apparatus and the primaryobject of the invention is to provide a simple means for reversing aplaten of a printing apparatus in a step-by-step manner.

A further object of the present invention to provide a platen reversingmeans for a printing apparatus of the type including a platen movablysupported therein for supporting a printing medium thereon.

Another object of the present invention is to provide such a reversingmeans wherein a manually operated means or an automatic circuit meansmay be utilized to reverse the platen.

Still another object of the present invention is to provide, in such areversing means, a first and second ratchet means operatively connectedto said platen and an electrically operated means for operating saidfirst and second ratchet means so as to move the platen a predeterminedamount in the reverse direction.

Further objects of the present invention will become apparent as thisspecification proceeds.

FIG. 1 is a perspective view of a typical printing apparatus of the typewhich may utilize the platen reverse mechanism of the present invention;

FIG. 2 is a fragmentary perspective view of the platen reverse mechanismof the present invention; and

FIG. 3 is a side view of the ratchet wheels for driving a platen in aforward and reverse direction and the drive pawls cooperating with saidratchet wheels.

Generally speaking, the present invention resides in a printingapparatus of the type including a platen for supporting a printingmedium and is a means for reversing the platen in a stepby-step manner.There is a first ratchet means operatively connected to the platen andarranged so as to move the platen in a reverse direction. A secondratchet means is also operatively connected to the platen and arrangedso as to stop movement of the platen in the reverse direction.Electrically operated means are provided for operating the first andsecond ratchet means so as to move the platen a predetermined amount inthe reverse direction. A manually operated means for energizing theelectrically operated means is provided and a circuit means forautomatically energizing the electrically operated means may beconnected in parallel with the manually operated means. The circuitmeans is adapted to operate in response to a coded input means. There isa switch means responsive to movement of said electrically operatedmeans so as to deenergize the electrically operated means when theplaten is moved a predetermined amount in the reverse direction.

In a specific embodiment of the present invention, the aforementionedelectrically operated means comprises solenoid means and linkage means.The linkage means is connected between the solenoid means and theaforementioned ratchet means.

Referring now to the drawing, the structure of an illustrativeembodiment of the present invention can be visualized in conjunctionwith the following description.

Referring specifically to FIG. 1, it can be seen that a typical printingapparatus, indicated generally by the reference number 10, isillustrated. The printing apparatus 10 may typically be an electrictypewriter, but may also be any type of business machine having a platensupported on a carriage and adapted to support a printing medium, suchas paper. For purposes of illustration, how ever, the followingdescription will be directed toward the provision of a platen reversingmechanism for an electric typewriter.

The printing apparatus 10, hereinafter referred to as the typewriter 10,is provided with a manually operated means 11 for actuating the platenreverse mechanism. The manually operated means, hereinafter referred toas the key 11, is disposed near the top and lefthand side of a keyboard,indicated generally by the reference number 12. There are means 13 and14 on the typewriter 10 for receiving code tapes 15 and 16,respectively. In accordance with conventional practice, one of saidmeans, for instance 14, is effective to impress a code upon the tape 16as the typewriter 10 is operated, while the other of said means iseffective to operate the typewriter 10 automatically to print out theinformation stored on a previously coded tape 15. The operation of themeans 13 and 14- which correspond, respectively, to the means 23, 21 ofthe Davidson et al. Patent 2,832,455 issued Apr. 29, 1958, will bediscussed further in conjunction with FIG. 2.

The balance of the typewriter 10 elements illustrated in FIG. 1 aretypical of all typewriters of the character hereunder consideration andneed not be discussed in this description.

Referring now to FIG. 2, the structure of an illustrative platen reversemechanism, indicated generally as 17, can be discussed.

A platen 18 is mounted on a shaft 19 so as to be rotated thereby. Thereis a ratchet wheel 20 mounted on the shaft 19 so as to rotate the platen18 in the direction of the arrow 21. There is a second ratchet wheel 22mounted on the shaft 19, adjacent to the ratchet wheel 20, so as torotate the platen 18 in the direction of the arrow 23 shown thereon.

The ratchet wheel 20 is normally used in typewriters of the type shownin FIG. 1 for advancing the platen step-by-step in a forward directionas the typewriter is operated. In accordance with the present invention,the ratchet wheel 22 is added to provide a means for reversing thedirection of the platen 18.

There is a drive arm 24 arranged so as to ride on a cylindrical surface22' in the space between the ratchet wheels 29 and 22. The drive arm 24has a pawl tooth 25 fastened thereto so as to drive the ratchet wheel 22in the direction of the arrow 23 when the drive arm 24 is driven in thedirection of the arrow 26. In most instances, gravity will hold the arm24 in contact with surface 22'; but if desired spring means (not shown)maybe provided to bias said arm 24 resiliently to such contact.

The drive arm 24 is pivotally connected to the end of a first extension27 of an L-shaped member 28. The L- shaped member 28 is pivotallymounted on a shaft 29 at a point where the two extensions of said member28 meet. The shaft 29 is rigidly supported in the typewriter 10.

There is a stop pawl 30 pivotally mounted about the shaft 29 and adaptedto engage the ratchet wheel 20 when actuated. A specific means formounting the stop pawl 30 about the shaft 29 will be discussed inconjunction with FIG. 3.

There is a linkage, indicated generally by the reference number 31,connecting the end of the second extension 32 of the L-shaped member 28to a lever 33 connected to the armature of a solenoid 34. The linkage 31has a pivotal connection means 35 connected directly to the end of theextension 32 and a second pivotal connection means 36 connected directlyto the armature lever 33. The pivotal connection means 35 has aninternally threaded shank portion 37 for receiving a first threaded end38 of a connecting bar 39. Similarly, the pivotal connection means 36has an internally threaded shank portion 40 for receiving a secondthreaded end 41 of the connecting bar 39. The internally threaded shankportions 37 and 40 and the threaded ends 38 and 41 of the connecting bar39 provide a means for adjusting the position of the drive arm 24.

There is a pair of spaced apart stop rings 42 and 43 independentlyadjustably fixed to the connecting bar 39, and spring means 44 issleeved upon the connecting bar 39 and constrained between the stoprings 42 and 43. There is a link 45 having a first end sleeved on thebar 39 and resiliently supported intermediate the ends of the spring 44,and having a second end connected to an extension 46 of the stop pawl 30by a pivotal connecting means 47. It can be seen that the pivotalconnecting means 47 has an internally threaded shank portion 48 forreceiving a threaded end 49 of the link 45. The internally threadedshank portion 48 and threaded end 49 are a means for determining thetension on the member 45 and, consequently, the holding power of thestop pawl 30. The link 45, therefore, is resiliently connected to thelinkage 31 and pivotally connected to the stop pawl 30. Because of thisresilient connection, the stop pawl 30 is resiliently engaged with theratchet wheel 20 when the drive arm 24 is operated.

There is a spring means 50 connected between the pivotal connectingmeans 36 and a stationary portion 51 of the structure of the typewriter10 so as to return the armature lever 33 to its normal position when thesolenoid 34 is deenergized. In many solenoid structures, the springreturn feature may be built into the solenoid.

The solenoid 34 has a pair of terminals 52 and 53. The terminal 52 isconnected directly to a first side of a normally-open switch 54 and afirst side of an automatic reversing circuit 74. The terminal 53 isconnected to a first side of a normally-closed switch, indicatedgenerally by the reference number 55, and through said switch to a firstside 56 of a power source. The second side 57 of the power source isconnected directly to a second side of the automatic reversing circuit74 and to a second side of the switch 54. There is a manually operatedmeans, indicated generally by the reference number 58, for energizingthe solenoid 34. In the illustrative embodiment shown in FIG. 2, themeans 58 comprises a lever member 59 pivoted on a shaft 60, a button 61on one end of the lever member 59 and an extension 62 on the oppositeend for closing the switch 54. Thus, whenever the operator of thetypewriter 10 presses the button 61 in the direction of the arrow 63,the extension 62 will move in the direction of the arrow 64 to close theswitch 54, thereby energizing the solenoid 34 through the switches 54and 55.

The switch 55 is constructed and arranged so that movement of thearmature lever 33 in the direction of the arrow 65 strikes the actuatorarm 66 of the switch 55 to open the energizing circuit for the solenoid34.

The automatic reversing circuit 74 is connected in parallel with theswitch 54 and is electrically associated with the means 13 and 14 sothat a suitable code index will be impressed on the tape 16 whenever thebutton 61 is depressed, and so that the solenoid 34 will be energizedwhenever the requirement for such an energization is programmed into thecoded tape 15. Therefore, the automatic reversing circuit 74 is acircuit means for automatically energizing the solenoid 34 and operatesin response to coded input means. Specific circuits for providing anelectrical output to operate a solenoid or for closing a circuit topermit current to fiow to the solenoid are well known in the art. Forinstance, a proper transistor having a base electrode adapted to receiveinputs from a tape reader and an emitter-collector circuit connectedbetween a power source and a solenoid will oper ate the solenoidwhenever a sufficient biasing voltage is applied to the base electrode.Similarly a silicon controlled rectifier having a gate electrode adaptedto receive inputs from a tape reader, an anode electrode connected to apower source and a cathode electrode connected to a solenoid willoperate the solenoid whenever a sufficient current is applied to thegate electrode. Since such circuits are Well known in the art, it willnot be necessary to describe an automatic reversing circuit, in detail,in this specification. See, for instance, the Bryce Patent 2,254,931issued Sept. 2, 1941 showing a reader corresponding to means 13, whichreader is connected to a work circuit by means of an amplifying circuit;the Dodge Patent 2,555,734 issued June 5, 1951 showing an automatictypewriter comprising a reader and the manner in which the reader iselectrically connected to solenoidoperated keys; and the Prince Patent2,897,267 issued July 28, 1959 showing a reader and an amplifier forconnecting the reader to a relay.

Referring now to FIG. 3, a fragmentary side view of the platen reversingmechanism 17 can be discussed.

As stated previously the drive arm 24 is pivotally connected at the endof the first extension 27 of the L-shaped member 28. Specifically, andas shown in FIG. 3, the drive arm is pivotally mounted on a stud 67extending from the extension 27 and is secured thereon by a snap ring68.

The stop pawl 30 is adjustably mounted on a cam 69 which is rotatablymounted on the shaft 29. The cam 69 may be rotated with respect to thestop pawl 30 so as to adjust the position of said stop pawl 30 withrespect to the ratchet wheel 20. There is a set screw 70 for securingthe stop pawl 30 to the cam 69. The cam 69, therefore, is a cam meansfor determining the amount of travel of the platen 18 in the reversedirection.

There is a drive pawl 71 engaged with the ratchet wheel 20 so as toadvance the ratchet wheel 20 in a forward direction when the pawl 71 isactuated. The drive pawl 71, therefore, is the conventional drive pawlfor advancing the platen 18.

With the above description in mind, and by making reference to thedrawing, the following operation analysis will serve to convey thefunctional details of the present invention.

The platen 18 is advanced, step-by-step, in the normal forward directionof the arrow 21 by means of the pawl 71 engaging and driving the ratchetwheel 20. The pawl 71 may be actuated by any number of techniquesnormally utilized in electric typewriters. However, in many cases, theoperator of the typewriter will desire to reverse the platen 18,step-by-step, for a predetermined amount. If the typewriter 10 is of thetype which may be automatically operated by a coded tape, the tape maycontain coded instructions for reversing the platen 18.

When the operator desires to reverse the platen 18, she will press thebutton 61 to close the switch 54. When the switch 54 is closed, currentcan flow from the power source through the switch 54 to energize thesolenoid 34, thereby rotating the armature lever 33 in the direction ofthe arrow 65. When the armature lever 33 strikes the actuator arm 66,the switch 55 is opened to deenergize the solenoid 34 and the spring 50returns the armature lever 33 to its non-operated position.

When the solenoid 34 is energized to rotate the armature lever 33 in thedirection of the arrow 65, the linkage 31 is moved in the direction ofthe arrow 72 to pivot the L-shaped member 28 in the direction of thearrow 73, thereby moving the drive arm 24 in the direction of the arrow26. When the linkage 31 is moved in the direction of the arrow 72, thelink 45, resiliently connected thereto, is also moved in the directionof the arrow 72 to engage the stop pawl 30 with the ratchet wheel 20,thereby stopping the reverse movement of the platen 18. The stop pawl 30may be adjusted on the cam 69 so as to permit the advancement of one ormore teeth of the ratchet wheel 20.

The key 58 is a manual means for reversing the platen one step at atime. That is, the button 61 must be pressed each time that the platen18 is reversed manually.

The platen reversing mechanism 17 of the present invention isparticularly advantageous because it can be energized by an automaticreversing circuit 74 cooperating with a coded tape receiver means 13 and14 or the like. If the reversing mechanism 17 was purely mechanical,electrical outputs as provided by the automatic reversing circuit 74could not be utilized to reverse the platen 18.

An electric typewriter having a platen reverse mechanism, such asdescribed supra, can ideally be used to draw figures, such as are usedto depict chemical formulae, and to type information at any point on achart in any sequence. With the automatic reversing circuit and codedtape receiving means, discussed supra, the typewriter can be programmedto perform the above-mentioned functions automatically. It may also beused to fill out forms or form formats having a sequence that does notcorrespond to the sequence of the data contained in the tapes.

In some electric typewriters of the type having a coded tape receivingmeans, manual actuation of the platen reverse mechanism of the presentinvention not only reverses the platen, but causes a code to be punchedor otherwise placed in a tape so that the manual operation may berepeated automatically. This, of course, is the theory of operation ofthe Flexowriter apparatus discussed in the aforementioned Davidson etal. Patent 2,832,455.

The solenoid 34, linkage 31, linkage 45 and L-shaped member 28 are anelectrically operated means for operating the pawl 25 and stop pawl 30.If the ratchet wheels 20 and 22 and the pawls associated therewith areconsidered, broadly, as ratchet means operatively connected to theplaten 18, the solenoid 34, linkage 31, linkage 45 and L-shaped member28 are an electrically operated means for operating said ratchet means.

I claim as my invention:

1. In a printing apparatus of the type including a rotatably mountedplaten for supporting a printing medium and means for driving the platenforwardly, means for driving the platen reversely in a step-by-stepmanner, the last-mentioned driving means comprising a first ratchet:wheel mounted on a common shaft with said platen, said first ratchetwheel being arranged to rotate said platen in the forward direction, asecond ratchet wheel mounted on said shaft adjacent to said firstratchet wheel, said second ratchet wheel being arranged to rotate saidplaten in the reverse direction, first pawl means for engaging anddriving said second ratchet Wheel, second pawl means for engaging andstopping said first ratchet wheel then said platen is rotated apredetermined amount in the reverse direction, electrically-operatedmeans effective, when energized, to shift said first pawl means in adirection afiirmatively to engage and move said second ratchet wheel inthe reverse direction and substantially simultaneously aifirmatively tomove said second pawl means into stopping engagement with said firstratchet wheel, manually-operated switch means for connecting saidelectrically-operated means to a power source, thereby to energize saidelectrically-operated means, and second switch means for disconnectingsaid electrically-operated means from such a power source, said secondswitch means being responsive to movement of said electrically-operatedmeans in response to energization thereof.

2. In a printing apparatus of the type including a rotatably mountedplaten for supporting a printing medium and means for driving the platenforwardly, means for driving the platen reversely in a step-by-stepmanner, the last-Said driving means comprising a first ratchet wheelmounted on a common shaft with said platen and arranged to rotate saidplaten in a forward direction, a second ratchet wheel mounted on saidshaft and arranged to rotate said platen in a reverse direction, a firstpawl for engaging and driving said second ratchet wheel and said platenin said reverse direction, a second pawl for engaging and stopping saidfirst ratchet wheel when said platen is rotated a predetermined amountin said reverse direction, a solenoid operatively connected to saidpawls and effective, upon energization, to move said first pawlaffirmatively to drive said second ratchet wheel and substantiallysimultaneously to move said second pawl to engage and stop said firstratchet wheel, a manually-operated switch for connecting said solenoidto a power source, thereby to energize said solenoid, and a secondswitch for disconnecting said solenoid from such a power source, therebyto deenergize said solenoid, said second switch being responsive tomovement of said solenoid in response to energization thereof.

3. The invention of claim 2 in which the operative connection betweensaid solenoid and said first pawl comprises a bell crank pivotallymounted on said apparatus, said first pawl being drivingly connected toone arm of said crank and said solenoid being drivingly connected to theopposite arm of said crank, whereby, when said solenoid is energized,said crank is pivoted to drive said first pawl.

4. The invention of claim 2 including a cam journal mounted on saidprinting apparatus, said second pawl being adjustably mounted on saidcam, thereby to determine the permissible amount of movement of saidplaten in said reverse direction, the operative connection between saidsecond pawl and said solenoid including resiliently yieldable means,whereby, when said solenoid is energized, said second pawl and said camare pivoted about the journal axis of said cam.

5. The invention of claim 3 including a cam journal mounted on saidprinting apparatus, said second pawl being adjustably mounted on saidcam, thereby to determine the permissible amount of movement of saidplaten in said reverse direction, a first linkage for connecting thearmature of said solenoid to said opposite arm of 7 8 said bell crank,and a second linkage having a first end 1,181,958 5/1916 Roberts 197-114connected to said second pawl and a second end resilient- 1,571,519 2/192 6 Gabrielson 197-114 1y connected to said first linkage. 1,821,0999/1931 Kurowski 197-114 2,453,282 11/1948 Thierne 197-114 ReferencesCited 5 2,476,917 7/1949 Ruben 197-114 2,555,734 6/1951 Dodge 197-20UNITED ST ATES PATENTS 2,633,828 4/1953 Adkins et a1 197 114 X 5 99/1951 Rltz 197149 2,791,311 5/1957 Yerks et a1. 197- 114 2,710,045 2/1955 Madsen 19791 2,832,455 4/1958 Davidson et a1. 197-114X 924,0966/1909 McLaughlin 197-114 954,637 4/1910 Kurowski 197 114 X ERNEST T.WRIGHT, Primary Examiner.

